Copper-Indium-Diselenid (CIS) thin-film solar cells on glass substrates or on foil substrates have been used more and more widely in the last few years because of their flexibility, their lightness and their efficiency. One advantage of these thin-film solar modules is also the possibility of connecting individual cells electrically (usually in series) on a common electrically insulating substrate already during the production process. There are usually a plurality of structuring steps required thereby for such an electrical connection: after deposition of the rear contact (frequently made of molybdenum), the latter is divided into individual cells which are separated from each other electrically. After the intermediate layers (e.g. CIS absorbers, buffer layer and (i-) ZnO layer) have been applied, these layers must be cut through at the edge of the adjacent cell up to the molybdenum. In a further structuring step, the subsequently applied front contact (for example conductive ZnO:Al) must then be separated in order to split up the short-circuited cells again.
It is necessary for this plurality of structuring steps to introduce into the individual layers of the thin-film solar module a plurality of tracks which extend parallel to each other and at a constant spacing from each other. In order to introduce these tracks, according to the concrete profile requirements of such a track, either mechanical structuring tools (such as for example mechanical graving tools or scoring needles) or structuring tools in the form of laser machining units must be used. Introduction of tracks of this type into the layers of solar modules is described for example in DE 10 2006 051 556 A1.
A fundamental difficulty when introducing the tracks is based on the fact that the solar cell modules, during production thereof, must pass through a plurality of process steps which take place partially also at high temperatures. Thus for example the introduction of first parallel tracks into a first layer of a solar cell module (for example in the rear-side contact) is effected by means of a first machining device based on a laser head (or a plurality of laser heads which operate in parallel at a constant spacing from each other). In a further process step, the thus structured solar module passes through a high temperature step. Consequently, the result is a (slight) distortion of the solar module as a result of the temperature so that the tracks of the laser process step which are originally introduced to be parallel are no longer exactly parallel after the high temperature step. In a further, third process step (for example by means of a mechanical process step), parallel tracks are then intended to be structured in again into the solar module in a further layer (for example an intermediate layer). It is hereby crucial that these parallel tracks are structured in at precisely defined spacings and parallel to those tracks which were introduced in the first process step (laser process step).